Process for the fractional extraction of petroleum hydrocarbons with alcohol



Aug; M, 11928. LGSOSZ T. A. WERKENTHIN PROCESS FOR THE FRAGTIONALEXTRACTION OF PETROLEUM HYDROCARBONS WITH ALCOHOL www2 Aug. M, ma.

T. A. WERKENTHIN PROCESS FOR THE FRACTIONAL EXTRACTION OF PETROLEUMHYDROCARBONS WITH ALCOHOL Filed Nov. 19, 1924 3 Sheets-Sheet 2 coa/a.;@Nain/6519 Mfr/@9c 77% co/yaL :Sfr-naw@ 72mm Aug. M, i928. 11,680,352

T. A. WERKENTHIN PROCESS FOR THE FRACTIONAL EXTRACTION OF' PETROLEUMHYDROCAHBONS WITH ALCOHOL Filed Nov. 19, 1924 3 Sheets-Sheet 5S14/vanto@ (147km :31g

Patented Aug. A i4, 1928.

, STATE THEoDonE A.

maar

FEE.

COMPANY, OF LIMA, OHIO, A CORPORATION OF OHIO.

PROCESS FOR THE FRACTIONAL EXTRACTION OF PETROLEUM HYDROCARBONS WITHALCOHOL.

Application led November 19, 1924. vSerial No. "150383.

My invention relates to a process for the fractional extraction ofpetroleum hydrocarbons with alcohol to produce a cracking stock andvarious grades -of lubricating oils.

According to my invention petroleum hydrocarbons are successivelyextracted from skimmed crude in a continuous manner with alcohol at alow temperature and inthe absence of'any substantial pressure whereby acracking stock is produced and a yield of lubricating oils is obtained.which is much greater than possible by the present method of voverheaddistillation. This may be readily understood whenit is considered thatin the overhead method of producing luv bricating stock, the oil suffersmarked cracking o f the heavy moleculesinto gases such as methane andethane with the corresponding production of' first unsaturated com-Ypounds and finally by complete rdehydrogenation of the 'hydrocarbonmolecules, passes into coke. In the production of this coke the mostvaluable lubricating components are destroyed.

In carrying out my invention, skimmed crude oil is utilized as astarting material a cracking stock and lubricating oils are selectivelyextracted therefrom with alcohol. The crude skimmed oil, that is onedeprived of its gasoline and kerosene content, is extracted first withalcohol so as to dissolve the most soluble components, this constitutingthe cracking stock. Thereafter the remaining oil which has been deprivedof the: l cracking stock is repeatedly subjected to an alcohollextraction treatment to produce a series of lubricating oils ofremarkably high character, and a residuum or'asphalt notable for its lowfree carbon-content. This resid- 4o ual oil or asphaltum furnishes anideal binder free from grit and impurities. The entire process iscarried out at a very 4low temperature, `the specifictemperatureemployed l being of course, determined some-jv what by the character ofthe material underoing treatmen To furnish the necessary' eat, steamcoils are -preferably employed and the extract is maintained at atempera ture that, as stated may :vary,but usually ranges between 150and 175 F. or the bolling point of the alcohol solvent. However,

to be steamed once.

as indicated, the temperature employed may vary, depending on the typeof oil treated.

For example, using a Galena Gulf cbastal crude, which is an oil havingan asphalt base, the extraction has been carried out at 100 F. Theprocess, as compared to the overhead method of distillation, ischaracteri'zed by its great fuel economy since the heat is savednecessary to raise the oil from the temperature at which crackingcommences which in the skimming operation represents the end point ofthedistillation of the crude to be used in the process, to the temperatureof,coking which runs about 800 F., and is the end point of the ordinarycoking distillation. Additionally, the heat required to reduce theparaffin distillate after cold pressing to the overhead lightlubricating oils and the residual red oils, is substantially entirelsaved, for the separation is effected by so ution and extraction withalcohol at a relatively low temperature. Further, the red oils producedin the reduc- Y ing stills need to be steamed lon an average three timesin order to produce satisfactory results with the shake tests while theoils resulting from the present process need only In this connection, itshould be notedthat not only is there a sav- 80 ing in steam but thetime necessary for the steaming operation is greatly reduced. Incomparing the overhead distillation system with my process, itwill beseen that all the fuel expenditure required in the latter is thatnecessary to'keep the starting material and the intermediate products ata tempera- -ture of 150 to 175 F., and to vaporize the alcohol'in thecontinuous system, since, the recovery and reuse of the alcohol iscontemplated In considering the heat necessary to vaporize the alcoholat the temperature stated, it should be noted that the heat ofvaporization of alcohol is only. 370 B.

t. u. per pound of alcohol whereas the heat of vaporization of water atthe same temperature is about three times as large. It is' thereforeobvious that the extraction process .employin alcohol effects a greatsavin in fuel. Ex aust steam may be employe as the fuel, and this is theonly sourcel of heat necessary to produce the variousv products.

ure also indicates the 'arrangement of 50 Apparatus suitable forcarrying out my invention is illustrated in the accompanying drawings inwhich:

Figs. 1, 2, 3 and 4 are elevations of successive extraction units;

Fig. 5 is a general plan view of extractor unit No. 3, which is typicalof the other units and shows the arrangement of the extractorbaiileplates, the exhaust steam coils and the perforated alcohol tanks;

Fig. 6 is a detail of the alcohol dehydrator and storage tank; K

Fig. 7 is a diagrammatic representation of asupplementary unit wherebycrude red oil stock may be brought, within certain limits, to anydesired viscosity.

The apparatus set forth in Fig. l which for convenience will be referredto as unit 1 will be described in detail. Figs. 2, 3 and 4 howsuccessive extraction units, similar to extraction unit/1 and will bereferred to as units 2, v3 and 4. The size of the different elements ofthese latter units differ somewhat from those of unit 1 but otherwisethere are no essential differences between the various units and thedescription of Fig. 1 will therefore adequately serve for the others.

Referring to Fig. 1 unit 1, comprisesv an extraction-tank 1, a settlingtank 2, a conduit 3 therebetween, an extract alcohol still 4 connected;to the settling tank 2 by the conduit 5, an alcohol condenser 6, and anl alcohol storage tank 7 having as an integral part thereofanalcoholdehydrator chamber 8, the construction of which will be described -lateron. Conduits 9, 10 and 11, serve to connect the various elements to makethe unit operative. 4The extraction ltank 1 is provided withan'oil inlet12 and outlet 16 to unit 2 and is in operative connection with thesafety condenser13 by means ofthe conduit 14. The conduit 11, connectswith the bottom alcohol pipe 17, provided with branches 15 whichterminate in perforated alcohol coils 18 as shown in Fig. 5. The heatnecessary to carry out. the process isfurnished by the extractor steamcoils 19 as indicated more in detail in Fig. 5. This filgt e bailleplates 20.

,The settling tank 2 'is provided with a conduit 21 to allowthe removalof any undissolvedoil which may be mechanically carried over from theextractor tank 1. Conduit 22of the alcohol still 4 allowsy thecollection of the portion of the oil extractedl by the alcohol. Thealcohol stillfl is heated to the necessary temperature by means of vthesteam coilsv 23. The alcohol condenser 6 is provided with the usualwater pipes The alcohol storage tank 7 is divided by the partition 25 soas to form a dehydrator chamber 8 whichis provided with means forholding a dehydrating chemical wherebythe small traces of water whichmay have been extracted from the oil and distilled over with the alcoholmay be removed. This may comprise rods or plates 26 carrying bags orcanvas plates 27. The alcohol storage tank 7 is also provided with avent 28.

The process may be carried out as follows: The oil introduced into thesystem may be either a paraffin base crude oil or an asphalt base crudeoil or a mixed asphalt-parailin base crude oil. All the natural gasolineand refined oil is topped from the crude oil, the exact amount takendepending on the nature of the crude which naturally has varying amountsof lightl fractions in it: Itis important that in the topping operationcare be taken to avoid cracking as this breaks up some of thelubricating stock.` If a paraffin base oil is used the extractedfractions of oils must bechilled and have the parain cold pressed but ifan asphalt base oil is used, the latter may be directly introduced intothe system Without any subsequent treatment of the extracted oils otherthan color treatment.

The skimmed crude oil produced as described, for example, 100 barrelsvispumped into the extractor tank 1 of unit 1 and allowed to ow through thebailed compartments thereof while the alcohol introduced through coils15 and 17 is extracting the light portion or cracking stock from theoil. The dissolved oil-extract is allowed to run into thesettling tank 2to allow any undissolved oil, which may have been carried alongmechanically to settle out. The oilextract overflows into still 4.-where the alcohol is distilledoff and passes into the water condenser 6to be condensed. The condensed alcohol runs into storage tank 7 firstflowing into compartment 8 to be dehydrated by means of a dehydratingchemical suitably suspended therein. From the storage tank 7 the alcoholis returned by gravity to the bottom of the extractor 1 and risesthrough the oil dissolving the lightest portion thereof; againoverflowing into the small settling tank. The oil or cracking stockproduced would amount to thirty-five barrels or generally speaking 35%ofthe oil introduced into thev system.

-The remaining undissolved oil flows by there has itslight lubricatingcomponents extracted by alcohol. The dissolved oil-extractl produced inthe extractor of unit 2 passes into a settling tank similar to that ofunit 1 and thereafter to an alcohol still where the lalcohol is removedby distillation from the extract andthe extracted oil j which is a lightlubricating oill having the characteristics later referred to sinks tothe bottom to be` withdrawn as it accumulates just as in the first unit.The quantity of this light lubricating oil is about 10 barrels or 10% ofthe oil introduced into the system. The4 liao alcohol in returned to theextractor of unit 2 and used over and over again. The size of theextractor, the ratio of oil to alcohol, and

, the length of time that the oil remains in the extractor determinesthe amount and also to some extent the quality of the oil extracted.

The remaining oil deprived of its cracking such as alcohol still7condenser and etc. Inl

unit 3 the lubricating oil of 250-310 viscosity is extracted from theoil in the same manner as the preceding two units. The quantity oflubricating oill extracted' in unit 3 is about thirty-five barrels or35% of the e oil introduced into the system. The undissolved oil isallowed to run by gravity to the extractor of unit 4 where heavylubricating oil of high viscosity may be extracted. The

' heavy lubricating oil obtained from unit 4 system and is part of thelubricating finish' represents about a 10% fraction of the oilintroduced into the system as well as does the residuum so each of theseWould be 10 barrel fractions, assuming as stated that the initial amountof crude oil introduced into the system is 100 barrels. The residuumfrom this last extraction will, in general, be of the nature ofasphaltum, its precise quali-v ties depending on whether asphalt baseoil or paraliin base or mixed baise oil is used in the process. Thecarbon content of the residual asphaltum will be directly proportionalto the carbon content of the topped crude; that is, all the free carbonis apparently left behind in the residuum and will roughly be ten timesthat of the carbon content of the original topped crude as it will havebeenconcentrated from one hundred volumes toten volumes of oil. Forexample, if the topped crude has one-fourth of one per cent free carbonthen the free carbon of the 'residue will be two and one-half per cent.

The oil which is drawn olf from the alcohol-e`xtract still of each unitis dried to recover any traces of alcohol except in the case of thecracking stock, which may, if desired, be sent to the pressure stillsimmediately upon being drawn off from the bottom of the alcohol still.In some cases, the number. of units may be increased and differentgrades of-oil produced.

Crude red oil stock as produced in unit 3 may be brought to any desiredviscosity (within certain limits) by being circulated through asupplementary unit 3A indicated diagrammatically in Fig. 7 and extractedthere with alcohol kept at a slightly lower temperature,'say 130 degreesF. This unit is run independently of the four units of the ing plant.The oil extracted from the crude red oil as derivedfrom unit 3^ may bereturned 'to the crude to be run through thesystem again or used thesame as' the light oil extracted in unit 2. .By this method a smallportion ofthe red oil is extracted but those components which arediluting the oil are gotten ridy of, thus leaving the unextracted oilfrom unit 3A, the red oil of the desired viscosity. After pumping theoil through the supplementary unit 3^ continuously for the requiredlength of time for example, three hours which it takes to extract thelight portion of the crude red oil, it is freed of any traces of alcoholand after a treatment for color is ready for the market. Supplementaryunit 3A is intended to be used when necessary only as a correctivemedium. The properties, nature and amounts of .the different productsobtained by the process set forth is indicated by the following: Sincethe initial starting material is the product which has been skimmed ofgasoline and kerosene content just below the point at'which crackingcommences as previously described, this skimmed crude oil has all thelubricating'components and some light components found in the spindleoils left in. Some Gulf coastal crudes may be used directly. As "anexample of the basic stock suitable for use in the process the followingis given: gravity 18 500O F. l

This stock is extractedy by means of the alcohol in such a way that themore soluble components are dissolved first. These more solublecomponents are low gravity and low viscosity oils between 23-25o B.gravity for the'85 to 10()` seconds Saybolt viscosity cracking stockwhile the less soluble components have up to 26.6 degrees B. gravity andthe high viscosity of 400-500 seconds Saybolt of heavy lubricating oils.This phenomenon of low gravity and low viscosity andfvice versa has beenobserved in the products obtained in the process from asphalt as well asfrom paraiiin base oils which seems to indicate that it is not alwaysthe low gravity oil that possesses the high viscosity as has beengenerally assumed.

A feasible explanation of this 'is that vthe molecular componentscontaining oxygen and 4 sulfur have a tendency to lower the gravity .buthave no particular influence on the viscosity of the oil.

The cracking stock oil which is extracted in unit 1 will vary from 20%to 35% depending on the nature of the skimmed crude used as a startingpoint. It will have a gravity of 23-250- B., a viscosity of .85 to 100.seconds Saybolt at 100 F., a flash point of 250 F., and a lire point of290 F. This stock is suitable forlight spindle oils but as itconstitutes such a large percentage of the crude it is advisable to useit4 as cracking f stock. It is intended to use this oil withoutcompletely recovering the traces of alcohol after 'it is drawn olf thealcohol-extract still.

, flash point y An example of the cracking stock obtained is as follows:

Gravity 24.4 B, Flash 305 F. Viscosity, 112 seconds at 100 F. Cold test36 F.

The light lubricating oil produced in unit 2 has a vscosity'of 180-215seconds Saybolt at 100 F. and a gravity of about 25 to 25.5O B., a flashpoint of 350 F. and a fire point of 390 F. The oil constitutes about9-12% of the oil charged. It shows a fair steam r shake test withoutsteaming out but, in order to show a perfectly acceptable test, it willhave to be steamed out once unless clayed with an acid-clay treatment toproduce the desired color. The untreated oil in a thin film has a goldenyellow color while in a four ounce bottle it is deep ruby in color oropaque.. An example of the light lubricating oil obtained in unit 2 isas follows:

Gravity 25.9 B. Flash 340 F. Viscosity, 160 seconds at 100 F.

The third and most important product of the process is an oil of 290-350seconds Say- I bolt viscosity at 100 F. This high grade oil forms fromabout 25% to 38% ,of the oil charged into the system. It has a flashpoint of about 430 F. and a lire point of. l180 F. v

gravity of 26 B. to 26.8 B. vThis oil will also require a slightsteaming to stand up to the shake or steam test perfectly. Its color isthe same as the lighter oil and will require acid-clay or acid treatmentto produce the desired color. An example of the medium lubricating oilis as follows:

Gravity 26.1 B Flash 370 F. Viscosity, 306 seconds at 100 F.

y as does the oil produced in unit 3. An example of the heavylubricating oil obtained is as follows:

Gravity 26.5 B. Flash 390 F. Viscosity, 496 seconds Saybolt at-- 100 F.

It is to be especially noted that the various lubricating oils have tobe cold pressed if a paraffin base oil or mixed base oil has been usedas a basis for the topped crude. This A It has a remarkable high coldpressing is accomplished just as ordinarily in cold pressing lubricatingoil stock but as the extracted oils the way they come from theextract-alcohol still contain a small quantity, say one-fourth tothree-fourths of one per cent of alcohol, they have a remarkable lowviscosity due to these traces of alcohol and can be easily pumped andotherwise handled for color treatment and cold pressing and presentsthem in a very favorable condition for chilling and cold pressing. Afterthe color has been obtained and the oil freed from its paraffin content,the remaining traces of alcohol may be removed.

The residuum or asphalt comprises about `81l% of the stock charged intothe system and is best converted to true asphalt by blowing to producethe desired consistency. At 100 F. this residue-oil iiows very slowly,has ashiny black appearance and is sticky to the touch. A remarkablefeature of the asphalt is that only a small per cent of free carbon ispresent unless found in such line colloidal suspension but it does notshow up when the mass is dissolved in benzine and filtered. d

Any of the standard methods for dehydrating alcohol may be employed toobtain the anhydrous product used in the process. The alcohol may bemade anhydrous in several ways but the one which I have found mostsatisfactory is the following:

The alcohol is stirred in a tank for about twenty-four hours with thetheoretical quantity of fresh lime (calcium oxide). The purer the gradeof llme used, the less will be the loss due to mechanical absorption ofthe alcohol. The lime is now 'allowed to settle and the clear orslightly limpid alcohol is decanted off and is mixed with dehydratedpowdered copper sulphate or blue stone and' placed in the still. Thedistillate from this 1s water free alcohol. `It is not Ahol, but onethat does not indicate a blue color when tested with the white anhydrouscopper sulphate has been found to give the best results when used in theprocess. The copper sulphate left in the still is dissolved in hot waterand allo'wed to recrystallize in a tank. The blue stone thus obtained isagain made anhydrous and may be used over and over. The, alcohol whichremains in the lime may be regained by steaming out the lime accumulatedfrom several batches and concentrating the dilute alcohol infractionating stillheads but whether this method of recovery is employedor not depends on the market price of the alcohol used.

Only the initial amount of alcohol required for the process is large andthe amount required laterv on is just that needed to replace the slightloss from evaporation from the continuous system.

In order to insure the anhydrous nature of the alcohol as it is keptcirculating. around in the continuous system, chamber 8 of the alcoholstorage tank 7 is provided with bags or canvas plates 27 filled withanhydrous copper sulphate which is in intimate contact with the alcoholthus taking out small traces of water that may have been extracted fromthe oil and distilled over with the alcohol. From this chamber the thusdehydrated alcohol overflows into chamber 8 which serves as the realstorage tank. The copper sulphate is removed froml time to time andexamined. Its color will indicate ,whether it is anhydrous or has takenup its live molecules of water of crystallizatlon. The copper sulphatein its anhydrous form has byweight roughly four times the efficiency oflime in removing water from alcohol and has the additional advantage ofbeing economically recovered.

The various impurities usually contained in the commercial grades ofalcohol do not effect the amount of oil dissolved by the alcohol in theminute quantities that they are present excepting possibly pyridine aseswhich impart a; somewhat disagreeable odor to the o1l. It may befeasible to obtain alcohol free :from this undesirable component. y

The alcohol needs no uriiications, unless dehydrating the traces o waterthat are carried along with the alcohol from the extractalcohol still tothe condenser, may be spoken of as purification. That is one of the ad,-vantagcs of the process that the alcohol needs no troublesome process ofrevivifying and can be used an indefinite length of time.

.It is desired to indicate that the total `yield of lubricating oilsobtainable when us- 40 nmg my process may be as high as 30 per cent ofthel crude which is almost two and onehalf times the usual quantityobtainable with the overhead distillation rocesses now in use. On theother -handi Ait is not desired to produce this maximum amount oflubricating oils, my process still represents the most economicalmethodof producing cracking stock for the pressure stills.

The contention of superlor quality oil produced by my process is basedon the following considerations: The light gravity oil produced containsa homogeneous series of hydrocarbons that, as shown by a series ofcarbonizationl tests, lwill withstand high temperature better and 4withthe production o less lcarbon that the oils produced by ordinarydistillation.

The substances may have almost identical boiling points 'and differ inother essential properties. -This state'of ai'airs occurs without4 endin organic chemicals and also applies to components of crude petroleum.Thus, -two substances may have identical vaorization temperatures yet madiHer wide- 65 y' in the temperature at whic decomposivarying betweention occurs. The diderential solubility of the components of crude oilin the alcohol eliminates this extensively.

The total value of all the products produced in the process as comparedwith the total value of the products ordinarily pro# duced will show agood margin in favor of my process.

Another big factor of economy of the process is the construction ofthevarious units. As there is no pressure on them, they may be of lightconstruction eecting a great saving of material in the structural Aand4foundation aswell as in the boiler construction. The highesttemperature experienced inthe process will be the boiling point of theanhydrous alcohols which is never more than 212 F.

Furthermore, no fire of any kind is in contact or in the vicinity of theoil or alcohol during the operation of the process; thus giving areduction in the tire hazard with a corresponding saving on theinsurance rates. To a large extent the fuel consumption and powerproduction may be centralized and b the use of steam the process maybema e entirely automatic if the temperature control of the extractor andthe rate of flow of the skimmed crude through the system isautomatically regulated. The extracting of the oil by thealcohol isautomatic as designed, and depends on the rate of distillation of thealcohol from the extract in the extract-alcohol still. A saving in labor-cost is edected by the automatic Aoperation of the rocess.

What I claim 1s:-

1.l The process of treating skimmed petroleum oils comprisingsuccessively extracting the `same with heated anhydrous alcohol at atemperature somewhat below its boiling point, and recovering from theextraction products, a cracking stock and lubricating oils and alcoholfor use in the process.

2. The process-of treating skimmed petroleum oils comprisingsuccessively extracting the same with heated alcohol at a temperaturevarying between 150 and the boiling point of the alcohol to obtain acracking stock and lubricating oils.

3. The process of treating skimmed petroleum oils comprisingsuccessively extracting the same with alcohol at a temperature 150 and175 F. to obtain a cracking stock and lubricating oils.

4f., The process of treating skimmed petroleum oils comprisingsuccessively extracting the same with anhydrous alcohol at a temperatureranging between 150 and the boil? ing point of the alcohol.

5. The process of treating skimmed petroleum oils comprisingsuccessively extracting the same with anhydrous alcohol at a temperatureranging between 150 and 175 F.

6. The process of treating skimmed petroleum oils comprisingsuccessively extracting the same with heated alcohol at a temperaturesomewhat below its boiling point and in the absence of any substantialpressure above atmospheric, separating the oil ex-` traction productsfrom the alcohol, passing the alcohol in contact with a dehydratingmaterial and reusing the alcohol in the process.

7. The process of treating skimmed petroleum oils comprisingsuccessively extracting the same with heated alcohol at a temperaturesome-what below its boiling point and in the absence of any substantialpressure above atmospheric, allowing any undissolved oil mechanicallyentrained in' the extract to settle, separating the oil settled from theextract and then di'stilling the mixture to separate the alcohol and theextract oils therefrom, passing the alcohol infcontact with adehydrating material and reusing the alcohol resulting from the latterste lii testimony whereof I hereunto a'ix my signature.

THEODORE A. WERKENTHIN.

